Sticks and Stones…

I will spare you the details, but this picture is taken 1 1/2 weeks after my foot caught and twisted on a bottom stair.

While this is obviously not a dog or cat paw, I thought I would use the opportunity to talk about injury – what happens and how it heals.

In my case, when I twisted my ankle, the ligament that holds the ankle bone to the leg bone (technically speaking) stretched too far. Instead of the ligament breaking, it broke the tip of the fibula (skinny leg bone) off. Lots of other ligaments and tendons and veins were stretched to and beyond their limits.

Injury/Inflammation

When a bone is fractured and trauma occurs to the surrounding tissues, the short term response, other than nauseating pain, is an influx of inflammatory cells to the area. They are attracted by damaged tissues releasing messengers into the bloodstream. Small vessels in the skin break and spill blood which later becomes a bruise. With the influx of blood, cells, and inflammation, swelling begins pretty soon after the injury.

Repair

The goal here is to bring cells to the area who will help with wound repair. The vessels will clot with platelets and a sticky fibrin matrix that is found in the blood, and the bruise will be reabsorbed with the help of macrophages – the clean-up white blood cells – who come to eat and digest the red blood cells. Other cells come to the area to help reconstruct the connective tissues. Spindle cells and fibroblasts heal the tendons and ligaments that were torn or stretched or pulled during the strain. Other cells rebuild the broken vessels and begin removing the dead inflammatory cells and their products as the swelling begins to drain away.

Broken Bones

Broken bones (fractures) repair themselves in a little more complicated form, but they still follow the same basic protocol of injury, inflammation, and repair. The bone forms a sort of inflammatory callous around the fracture site, where inside this injury cells form a sort of “wound soup”. The bone repairs with cells that both make bone (osteoclasts) and destroy bone (osteoblasts) in order to properly remodel and repair the fracture. Stability is a must for this process. Any mobility will not allow the cells to create a latticework on which to reform the bone. Even if the bones are not completely aligned, if they are stable the bone can remodel enough to get a stable union, though it may not be completely straight.

Treatment

Short term treatment is rest, ice, and anti-inflammatory medication (elevation would be great too, but I can’t see a dog elevating a sore paw…). Dogs and cats shouldn’t take over-the-counter medications like aspirin, advil, or tylenol – there are safer alternatives that are labeled for dogs and cats to decrease inflammation and help with pain. If there is a fracture, stabilization may be necessary through surgery or a cast/splint, but that is dependent on the fracture itself. Over time rest is the best healer – short leash walks and crating during the day can help the body heal the rips and tears that the injury created – and no jumping!

So now I am healing, and hopefully your animal never has to deal with the pain of a broken bone or a ligament injury. My next post will involve a specific ligament injury – the cruciate ligament rupture (ACL injury in humans)